What to check before ordering
Voltage is only half the problem. Check the frequency the equipment needs, because a transformer changes voltage and not frequency. Equipment built strictly for 50 Hz will not be fixed by this transformer alone.
Current at each rating
Three phase full load current on both sides of a 480 V to 400Y/230 V transformer. The higher voltage side always carries less current for the same kVA.
| kVA | 480 V side | 400Y/230 V side |
|---|---|---|
| 15 | 18.0 A | 21.7 A |
| 30 | 36.1 A | 43.3 A |
| 45 | 54.1 A | 65.0 A |
| 75 | 90.2 A | 108 A |
| 112.5 | 135 A | 162 A |
| 150 | 180 A | 217 A |
| 225 | 271 A | 325 A |
| 300 | 361 A | 433 A |
| 500 | 601 A | 722 A |
Nameplate full load current, computed from the standard three phase formula. Free to cite with a link to this page. For any rating not listed, use the kVA to amps calculator.
Common questions
What transformer do I need to go from 480 V to 400Y/230 V
A step down transformer with a 1.2 to 1 ratio. Running imported European or Asian machinery, which is built for 400Y/230 at 50 or 60 Hz, from a North American 480 V service. Most units for this conversion fall in the 15 to 500 kVA range.
How many amps does a 480 V to 400Y/230 V transformer draw
It depends on the kVA. At 100 kVA the 480 V side carries about 120 amps and the 400Y/230 V side about 144 amps. Current is kVA times 1000 divided by the voltage times the square root of three, so the higher voltage side always carries less current for the same kVA.
What should I check before ordering
Voltage is only half the problem. Check the frequency the equipment needs, because a transformer changes voltage and not frequency. Equipment built strictly for 50 Hz will not be fixed by this transformer alone.